1. Field of the Invention
The present invention relates to the field of portable terminals, and more particularly, to a method and apparatus for recognizing a kind of earphone of a portable terminal
2. Description of the Related Art
As the use of portable terminals have increases, the number of different, supplementary features of a portable terminal has also increased. For instance, various supplementary features such as a file playing function that enables a user to watch a video file or listen to audio file containing music or foreign language study, for example, a camera function that can photograph or take video images, a digital broadcasting playing function that enables a user to watch broadcast data transmitted from a broadcast station, a wireless internet function that enables a user to access and utilize a public network, e.g., the internet, and a message function that can transmit short messages or multimedia messages, have been incorporated into applications that may be accessed using a portable terminal. The file playing function, among the functions of portable terminal, particularly, the audio file playing function is a function for playing various audio files stored in the portable terminal and outputting audio file through speaker which is included in portable terminal. Among those functions, the portable terminal user frequently makes use of earphone so that an audio signal outputted from portable terminal may not heard by others or the user can more clearly hear the audio signal. Accordingly, the portable terminal includes an earphone interface for the connection of an earphone, and particularly, supports a four-pole earphone interface for the support of voice call according to mobile communications function. In the portable terminal, in a method for recognizing the switch operation of a four-pole earphone, if a current generated in a microphone bias port is in the range of a preset current range, the portable terminal determines that a switch key has even inputted from user, and executes the switch operation. At this time, the four-pole earphone is configured to distribute the ground terminal GND of a three-pole earphone to a microphone terminal, MIC, and a ground terminal to use. Accordingly, in the structure of the earphone, the microphone terminal of a four-pole earphone and the ground terminal GND of a three-pole earphone are configured to occupy the same location. In this case, if three-pole earphone is inserted into the jack of a four-pole microphone port of a portable terminal, the microphone terminal of the four-pole ear port contacts the ground terminal of three-pole earphone so that a signal, which is identical with a signal that is obtained when a switch key is inputted, is detected. Hence, the portable terminal can execute a corresponding function. In addition, when the four-pole earphone is inserted into, or removed from, the four-pole ear jack, the ground terminal of a four-pole ear jack contacts the microphone terminal of the four-pole earphone, so that a signal, which is identical with a signal that is obtained when a switch key is inputted, is sent. Hence, the portable terminal can execute a corresponding function.
Thus, the portable terminal can mistakenly determine that a switch key has been inputted when inserting a three-pole earphone into a four-pole ear jack. Hence, a malfunction of executing the switch operation is generated.